Apparatus for heating meterial by means of microwave device



May 6, 1969 H. A. PUSCHNER APPARATUS FOR HEATING MATERIAL BY MEANS OF MICROWAVE DEVICE Filed July 25, 1966 INVENTOR.

United States Patent Int. Cl. 1105b 9/06 US. Cl. 219-10.55 9 Claims ABSTRACT OF THE DISCLOSURE A crane is fitted with a microwave system on the end of an adjustable boom for applying microwave energy to rock material to break apart the rock material.

The invention relates to apparatus for heating material by means of a microwave device, more particularly for the thermal breaking of rock and ore in the electromagnetic radiation field of an applied wave.

(It is known to cleave large blocks of rock and ore, for the purpose of subsequent comminution, by electric high frequency fields in the frequency region of 100 lc./s. to 3 gc./s. This method has the disadvantage that for producing the electric field, electrodes lying at a high potential have to be used. Moreover, there is a high degree of wear on the electrode material.

The observation underlying the invention is that electrically poorly conductive rock, for example, limestone, can only be rapidly heated in an electromagnetic radiation field above 300 megacycles per second. The known microwave devices are however unsuited for being use-d at rock Sites.

The electromagnetic energy has to be transferred to the material by means of hollow lines, the aperture of which has to be provided directly at the rock in order that the desired thermal wedge forms, the thermal stresses of which split the rock. The necessary mutual ad'justability of the microwave device and the material to be treated is not given with the known arrangements.

The invention consists in an apparatus for heating material by means of microwave energy comprising a microwave device having a microwave generator, a cooling device for the generator and a hollow guide radiator for directing the microwave energy onto the material to be heated, the microwave device being mounted on the boom of a crane whereby to enable application of microwave energy from its hollow guide radiator to the material to be heated.

With this movable apparatus, even blocks lying at the edge of a rock field can be reached. This device is also suitable for the thermal blasting of concrete roads and rock walls in quarries. A great advantage of the apparatus of the invention is that the hollow guide radiator from the microwave generator to the radiation aperture can be very short, so that the transmission losses occurring in the guide, which impair the overall efficiency, remain small. Moreover, another advantage is that the microwave device, which is suspended on the boom above the region being worked, is not endangered when heavy stone pieces break apart.

If two hollow guide radiators are provided, the apertures of which are spaced from each other by one to two metres, thermal wedges can be created in oppositely disposed sides of a block, which considerably accelerate the splitting, if for example with stratified stone they are applied to a growth boundary or a vein.

-In order to make the invention clearly understood, ref- "Ice erence will now be made to the accompanying drawings which are given by way of example and in which:

FIG. 1a and FIG. lb are perspective views of an apparatus according to the invention, having a single hollow guide radiator; and

FIG. 2 is a fragmentary view of another embodiment of the apparatus, with two hollow guide radiators.

In FIG. 1 a microwave device 1, comprising a hollow guide radiator 2, a microwave generator 3 and a cooling device 4- for the generator 3, with these parts enclosed by a sheet metal housing 5 is suspended on a running carriage 6 which is displaceable along a boom 7 of a crane. The microwave device 1 can in addition be displaced vertically by drive means 8. The boom is mounted on a turntable 9 on which, in addition to an electricmotor-operated lifting and rotating mechanism 10, an electric current supply device 11 and an operators cabin 12 with a transparent top 13 are disposed as counterweight. The turntable 9 is rotatably mounted on the chassis 14- of a motor vehicle 15. The microwave generator 3 is fed from the electric current supply device 11 through a cable 16 and the current supply device 11 is connected to the mains 17 through a heavy current cable 18 which is arranged on a mobile cable drum 19. Monitoring lines 20, for example a transmission cable 21 of a television camera 22 run from the microwave device 1 to the operators cabin 12. In the hollow guide 23 coming from the microwave generator 3, a rotary coupling 24 and a flexible hollow guide piece 25 are inserted in order to enable the hollow guide radiator 2 to rock and turn. The microwave energy is transmitted to the stone block 27 which lies within the quarry field 28, 29, 30', 31 at the radiation aperture 26. The block 31 is illustrated as already split.

The arrangement of FIG. 2 is generally similar to that of FIG. 1, but FIG. 2 shows the microwave device 32 with two hollow guide radiators 33, 34, two microwave generators 35, 36 and a single cooling device 37 for the generators. The microwave energy is transmitted from the radiation openings 38, 3-9 onto the two oppositely disposed sides of the block 40.

The arrangement of FIG. 1 or FIG. 2 can be operated from the operators cabin on the turntable, with the aid of electric drive means, by only one man. It is therefore particularly economical in use. The events taking place in the immediate vicinity of the radiation aperture can be picked up by a television camera 41 (FIG. 1) and displayed in the operators cabin on the screen of a television device 42, in order for example with long boom, to be able to better follow the application of the radiator and the formation of a rift in the rock, during the irradiation time. In order that no substantial losses of radiation by dispersion occur, the radiation aperture must be disposed directly at the surface of the block being worked on. Due to the uneven rook surface, the hollow guide radiator must be movable in order that the aperture can be brought into the necessary position. The mobility necessary for this is given to the radiator by the short, flexible hollow guide piece 25 and the rotary coupling 24. In order to avoid heavy shocks on application, the radiator is provided with a resilient mounting.

I claim:

1. An apparatus for heating material by means of microwave energy comprising a microwave device having a microwave generator, a crane having a movable boom, a cooling device for the generator and a hollow guide radiator for directing the microwave energy onto the material to be heated, the microwave device being mounted on said boom whereby to enable application of its hollow guide radiator to the material to be heated.

2. An apparatus according to claim 1, comprising a carriage mounted on the crane boom for movement therealong, the microwave device being mounted on the carriage.

3. An apparatus according to claim 1, wherein the crane boom is a telescopic articulated boom and the microwave device is mounted at its end.

4. An apparatus according to claim 1, wherein the crane is a rotary crane and is arranged on a mobile vehicle.

5. An apparatus according to claim 4, comprising a visual monitoring device disposed at an operating position of the vehicle, for indicating the relative disposition of the radiation aperture and the material to be treated, said monitoring device being connected to an appropriate transmitter at the boom head.

6. An apparatus according to claim 4, wherein the crane has a turntable and an electric current supply device for the microwave device is disposed on the turntable as a countenweight for the boom and for the microwave device provided on the end of the boom.

7. An apparatus according to claim 1, wherein the microwave device has at least one hollow guide radiator which is rotatable about its longitudinal axis.

8. An apparatus according to claim 7, wherein the hollow guide radiator is displaceable in the direction of its longitudinal axis.

9. An apparatus according to claim 1, wherein the hollow guide radiator has a flexible portion.

References Cited RICHARD M. YVOOD, Primary Examiner. L. H. BENDER, Assistant Examiner.

US. Cl X.'R. 219-1057 

